Impedance cardiography for determination of stroke index

Abstract

Stroke index obtained by impedance cardiography was compared with valuesobtained by dye-dilution technique in 17 subjects in 122 determinations made within 2 min of each other. Fifty of these determinations were done afterdrug administration, postural change, or saline infusion. All values obtained by both methods correlated significantly, but with wide scatter (r=0.49,n = 122, P less than 0.001). The series of determinations within each subject, however, correlated only in one subject significantly; thus any changesof stroke index measured by both techniques were not commensurate. In addition, the impedance stroke index values were significantly lower than the dye-dilution technique, impedance cardiography presently does not determine reliably absolute values of stroke index and is not suitable to evaluate changes of stroke index.